So why wouldn't you want it?
Bugs, simple as. Some people would rather someone else take the risk with an x.0 version - they'd rather wait for x.0.1. Case in point was the Exchange issues with 6.0 which were a real problem for anyone syncing their device with work email (like me).
And yes, there are plenty of bugs in 7.0, from unintentionally selecting messages to delete in iMessage to strange behaviour when searching in Mail, to some serious contrast issues (white text on a white background on the keyboard, anyone?). That's not to criticise Apple - I'm a software developer and I know that stuff like this happens. They'll get fixed sooner or later.
PS - for someone with a visual impairment, like me - the new interface *does* pose problems. Fortunately, most, though not all, of them are fixable via Accessibility.